The prior art is well aware of the construction and utilization of sheet stackers which automatically form a stream of sheets into a stack. U.S. Pat. Nos. 2,933,314 and 3,969,993 and 4,554,867 show the method and apparatus of forming a stack of sheets from a continuously moving stream of the sheets which enter the stack. The stack is then lowered away from the stream and is appropriately handled for compression and typing, if desired. With respect to compressing a stack, U.S. Pat. No. 3,739,924 shows that method and apparatus where the stack is compressed after it is in its lowered position on equipment for compressing and binding the stack.
In the lowering of the stack from its initial position of formation adjacent the stream and to its lowered position for lateral movement away from the stacker, such as shown in the aforementioned patents, the stack is not clamped or otherwise secured while it is moving downwardly, and there thus is a tendency for the sheets on the top of the stack to become upset as they slide along their support. This precludes a neat and undamaged arrangement of the sheets at least on the upper end of the stack.
The present invention overcomes the aforementioned problem of neatness and sheet damage, as well as the lack of compactness of the total stack, and it does so in an automated method and apparatus which permits the desired complete control of the stack in moving the stack away from its position adjacent the stream of sheets.
In accomplishing the aforementioned, there is both method and apparatus involved herein whereby the stack is clamped prior to its movement away from the stream, and it thus can be moved in a clamped relationship from its position of formation and on to its position of destination. As indicated, this method and apparatus pertains without the interruption, or even the slowing down, of the collection of the sheets into the stack and also the movement of the stack from its initial collected position and to the desired destination thereof.